Ultraviolet (UV) light energy has long been used in the disinfection of water, surfaces and air. The mechanism of disinfection and the effects that UV energy, particularly that in the UVC-germicidal wavelengths, is well understood. Recently, more UV applications have been made in HVAC equipment. HVAC equipment can range from small, stand-alone air cleaners to large commercial and industrial systems for buildings. In large systems, UV lamps can be mounted on rooftops or in equipment rooms.
Typically, these systems contain an air handling unit (fan), heating components such as electric coils or heat exchangers, air-conditioning coils, air filter elements, and the necessary enclosure and duct work to bring building and outside air into the equipment and deliver it back to the building. UV light can then be applied at several locations within this HVAC system. Common locations may be near the filters, near surfaces which may harbor mold and bacteria, near air-conditioning coils, near drain pans and possibly in a cross-section of the duct to disinfect the moving air stream.
Depending upon the application, the UV lamp fixtures can be mounted individually within the system or exterior to the ductwork incorporating fixtures that have the lamp itself protruding into the ductwork. Also, in some applications, the ballasts that power the lamps can be located within the duct and enclosed in a fixture. In many applications, the ballasts can be located external to the duct and connected to the lamps via wiring and conduit. Installations of these UV lamps are often complex and costly because the lamp fixtures typically require individual mounting and a separate supporting frame structure. Wiring these lamps can also be complex and costly as each lamp or lamp fixture via wire and conduit to operate. In addition, complex framework and fixture mounting can partially block the air paths that can contribute to loss of airflow and pressure drop.